Plot holes in time travel stories.

[ilikeitlikethat]

In Back to the Future (1985), I simply deduce that the time machine can move through time and subspace; otherwise... Who know's where Einstein (Doc's dog in 1985) would have wound up being displaced from the Earth for that period of time; Don't even get me started on the voidness of the vacuum of Space Marty should have been occupying in 1955 when he first went back; Hill Valley is a fixed location on an ever moving planet, so I deduce that this machine also travelled through subspace to find the space where Hill Valley is at that time of destination.
Or in other words;

Are there any that get you?

 

[Lord Lavender]

I would presume that the time machine would also take space into account as well as time. I have never thought that a time machine would dump you in space if the Earth was in a different place in orbit. I have also wondered if you went back in time and did something to change the timeline would it affect everyone perception of the world or just yours. Say you go back in time and save the dinosaurs by stopping the asteroid. Would the new sapient dinosaur world you would be going back to just feature yourself and every other person stays in this timeline while you alone exist in the alternative timeline or would this timeline be wiped clean completely.